The invention relates to a suspension arrangement for supporting an air conditioning system or a so-called air generation unit within the fuselage of an aircraft, and especially a high capacity commercial passenger transport aircraft.
There are various arrangements known in the art for supporting air conditioning systems, i.e. so-called air conditioning packs or air generation units, in the fuselage of an aircraft. Especially in high capacity passenger aircraft, of which the fuselage interior space is divided into an upper deck and a lower deck, it is known to support an air conditioning system on the aircraft structure, mainly in either one of two technologically different manners or concepts. The first concept, which applies especially to aircraft with an integrated air-supported air conditioning system, involves suspending the air conditioning system from the aircraft fuselage ceiling structure using suspension rods. The second concept involves supporting the air conditioning system standing on the cabin or freight compartment floor.
In the first concept of suspending the air conditioning system using suspension rods, the first step is to define the necessary force introduction points statically on each one of the various components of the air conditioning system and similarly also on the aircraft airframe structure in order to achieve the required weight-bearing suspension support as well as the necessary degree of safety. Namely, the suspension arrangement must be strong and secure enough, and provide a sufficient safety margin, to comply with applicable aviation regulations, which are especially stringent for overhead suspended installations. So-called suspension rods are used as the connection and force bearing elements. These rods must be specially designed and fabricated with a high precision tolerance to the specific required installation length for each suspension point, even though the rods allow a small degree of length adjustment.
In order to install this suspension arrangement in the aircraft, all of the rods are first individually pre-mounted on the defined force introduction points or load-bearing points on the aircraft airframe structure, and then the various individual air conditioning components or devices of the air conditioning system are installed and suspended on the bottom ends of the suspension rods. In this regard, the various suspension rods must be individually adjusted. In order to accommodate different patterns of the load-introduction points on the air conditioning system in comparison to the load-introduction points on the aircraft airframe structure, the individual suspension rods are arranged at various angles and with various lengths, resulting in a rather complicated and time consuming installation process.
Nonetheless, such a suspension arrangement, which is used, for example, in the known Airbus A319, A320, A321, A330 and A340 aircraft, is a very advantageous manner of installing and supporting the air conditioning system. Namely, during the installation, this suspension arrangement provides a high degree of flexibility, because essentially every load-bearing structure of the aircraft airframe can be utilized as a possible suspension point for a respective component of the air conditioning system. It is also possible to install the air conditioning system in the area enclosed within the belly fairing, namely outside of the main pressurized aircraft fuselage, whereby the air conditioning system is supported below the aircraft airframe structure, without using up any of the available space or volume within the aircraft structure itself.
The above mentioned second concept for supporting an air conditioning system is used, for example, in the known Airbus A300 and A310 aircraft, and involves mounting and securing the air conditioning system on a corresponding statically determined loadable area of a floor within the aircraft structure. While this installation concept is simpler than the above described first concept using suspension rods, this second concept also suffers certain disadvantages. Foremost, this installation requires a direct mechanical connection of the air conditioning system onto a strong, rigid, load-bearing floor structure within the aircraft fuselage itself. This, of course, limits the flexibility of the Id location at which the air conditioning system can be installed, and also necessarily reduces or encroaches on the available cabin volume and freight compartment volume that is available within the aircraft fuselage. Any attempt to install an air conditioning system in this manner in any area other than a pre-existing load-supporting floor of the aircraft structure would carry with it severe weight penalties, because it would be necessary to build an additional load-bearing floor area.
Neither of the two above described conventional air conditioning system installation and support concepts are well suited to installing an air conditioning system in the high capacity multi-deck passenger transport aircraft now under development, whereby it is desired to install the air generation units (AGUs) in extremely high areas within the aircraft fuselage structure and/or at locations that will only partially reduce the available cabin or freight volume available within the aircraft fuselage. Particularly, it is desired to install the air generation units at locations where the remaining volume within the fuselage above or below the respective air conditioning system will still be usable, for example as passenger cabin space or freight and cargo hold space. It is also important that the installation does not significantly add to the weight of the overall aircraft, and is simple and economical to carry out.
In view of the above, it is an object of the invention to provide a suspension arrangement for supporting an air conditioning system or so-called air generation unit (AGU) in a high capacity commercial transport aircraft in a manner that is simple and economical to install, comparatively light in weight, and high in load supporting strength and crash worthiness or safety in an accident situation. It is a further object of the invention to provide such a suspension arrangement for suspending an air generation unit in an extremely high and difficult to access installation space in the lower aircraft fuselage area. Moreover, the installation shall be such that the remaining volume above or below the air conditioning system shall still be usable as passenger space, cargo and freight space, or storage space. The invention further aims to avoid or overcome the disadvantages of the prior art, and to achieve additional advantages, as apparent from the present specification.
The above objects have been achieved according to the invention in a suspension arrangement for suspending an air conditioning system (or other system unit) in an aircraft. The suspension arrangement includes distinct first and second securing units or suspension mounting units. The first suspension mounting unit comprises plural suspension rods that are each secured at their bottom end to a respective component of the air conditioning system and extend vertically or substantially vertically upwardly from the air conditioning system. The second suspension mounting unit comprises a suspension frame that is secured to defined force introduction and support locations on the aircraft airframe structure below or within the outer enclosure of the aircraft fuselage. The respective upper ends of the suspension rods of the first suspension mounting unit are secured to defined force introduction and support locations on the suspension frame.
By providing these two distinct suspension mounting units with distinct functions, the invention achieves the above described advantages. The installation is very flexible and adaptable, yet simple and economical to carry out. The suspension frame provides a standardized array of load-introduction or suspension points, preferably on a single suspension plane, from which the suspension rods of the other suspension mounting unit may be secured and suspended. Thereby, the suspension frame is flexibly adaptable to different configurations of the aircraft fuselage structure or airframe structure at different locations at which the air conditioning system may be installed. On the other hand, the suspension rods more simply need to be connected only between the specialized load-introduction or suspension points on the various components of the air conditioning system at the respective lower ends of the suspension rods, while the upper ends of the suspension rods can be easily secured to the standardized or pre-established array of suspension points provided on the suspension frame. The array of suspension points on the suspension frame can already be adapted to generally match the locations of the suspension points of the air conditioning system. It is thus no longer necessary for the suspension rods to achieve the accommodation between differing patterns and locations of suspension points on the air conditioning system and on the aircraft air-frame structure respectively.